Sami2 is Another Model of the Ionosphere (SAMI2): A new low-latitude ionosphere model

Abstract. A quantitative division of the ionosphere into dynamo and motor regions is performed on the base of empirical models of space distributions of ionospheric parameters. Pedersen and Hall conductivities are modified to represent an impact of acceleration of the medium because of Ampére's force. It is shown that the currents in the F2 layer are greatly reduced for processes of a few hours duration. This reduction is in particular important for the night-side low-latitude ionosphere. The International Reference Ionosphere model is used to analyze the effect quantitatively. This model gives a second high conducting layer in the night-side low-latitude ionosphere that reduces the electric field and equatorial electrojets, but intensifies night-side currents during the short-term events. These currents occupy regions which are much wider than those of equatorial electrojets. It is demonstrated that the parameter σd=σP+σHΣH/ΣP that involves the integral Pedersen and Hall conductances ΣP, ΣH ought to be used instead of the local Cowling conductivity σC in calculations of the electric current density in the equatorial ionosphere. We may note that Gurevich et al. (1976) derived a parameter similar to σd for more general conditions as those which we discuss in this paper; a more detailed description of this point is given in Sect. 6. Both, σd and σC, appear when a magnetic field line is near a nonconducting domain which means zero current through the boundary of this domain. The main difference between σd and σC is that σd definition includes the possibility for the electric current to flow along a magnetic field line in order to close all currents which go to this line from neighboring ones. The local Cowling conductivity σC corresponds to the current closure at each point of a magnetic field line. It is adequate only for a magnetic field line with constant local conductivity at the whole line when field-aligned currents do not exist because of symmetry, but σC=σd in this case. So, there is no reason to use the local Cowling conductivity while the Cowling conductance ΣC=ΣP+ΣH2/ΣP is a useful and well defined parameter.

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The effect of vibrationally excited nitrogen on the low-latitude ionosphere

Annales Geophysicae ◽

10.1007/s00585-997-1422-2 ◽

1997 ◽

Vol 15 (11) ◽

pp. 1422-1428 ◽

Cited By ~ 7

Author(s):

B. Jenkins ◽

G. J. Bailey ◽

A. E. Ennis ◽

R. J. Moffett

Keyword(s):

Excited States ◽

Atomic Oxygen ◽

Molecular Nitrogen ◽

Low Latitude ◽

Vibrationally Excited ◽

Model Calculations ◽

Oxygen Ions ◽

Ionosphere Model ◽

Low Latitude Ionosphere ◽

Excited Nitrogen

Abstract. The first five vibrationally excited states of molecular nitrogen have been included in the Sheffield University plasmasphere ionosphere model. Vibrationally excited molecular nitrogen reacts much more strongly with atomic oxygen ions than ground-state nitrogen; this means that more O+ ions are converted to NO+ ions, which in turn combine with the electrons to give reduced electron densities. Model calculations have been carried out to investigate the effect of including vibrationally excited molecular nitrogen on the low-latitude ionosphere. In contrast to mid-latitudes, a reduction in electron density is seen in all seasons during solar maximum, the greatest effect being at the location of the equatorial trough.

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SAMI II: the NRL low-latitude ionosphere model

IEEE Conference Record - Abstracts. 1999 IEEE International Conference on Plasma Science. 26th IEEE International Conference (Cat. No.99CH36297) ◽

10.1109/plasma.1999.829391 ◽

2003 ◽

Author(s):

J.D. Huba ◽

G. Joyce

Keyword(s):

Low Latitude ◽

Ionosphere Model ◽

Low Latitude Ionosphere

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VLF/LF (Very Low Frequency/Low Frequency) Reflection Properties of the Low Latitude Ionosphere

10.21236/ada205976 ◽

1988 ◽

Author(s):

Wayne I. Klemetti ◽

Paul A. Kossey ◽

John E. Rasmussen ◽

Maria Sueli Da Silveira Macedo Moura

Keyword(s):

Low Frequency ◽

Low Latitude ◽

Very Low Frequency ◽

Low Latitude Ionosphere

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Disturbances of the Low Latitude Ionosphere During Extremes of Geomagnetic Activity

10.21236/ada628775 ◽

2003 ◽

Author(s):

Michael Mendillo

Keyword(s):

Geomagnetic Activity ◽

Low Latitude ◽

Low Latitude Ionosphere

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The role of storm‐time Electrodynamics in the Dawn and Dusk sectors across equatorial and low‐latitude ionosphere during 19‐21 December 2015

Journal of Geophysical Research Space Physics ◽

10.1029/2020ja029072 ◽

2021 ◽

Author(s):

Ram Singh ◽

S Sripathi

Keyword(s):

Low Latitude ◽

Low Latitude Ionosphere

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An investigation of the ionospheric F region near the EIA crest in India using OI 777.4 and 630.0 nm nightglow observations

Annales Geophysicae ◽

10.5194/angeo-36-809-2018 ◽

2018 ◽

Vol 36 (3) ◽

pp. 809-823 ◽

Cited By ~ 2

Author(s):

Navin Parihar ◽

Sandro Maria Radicella ◽

Bruno Nava ◽

Yenca Olivia Migoya-Orue ◽

Prabhakar Tiwari ◽

...

Keyword(s):

Electron Density ◽

Gravity Waves ◽

Satellite Mission ◽

Low Latitude ◽

Density Maximum ◽

Density Profiles ◽

F Region ◽

Equatorial Ionization Anomaly ◽

Low Latitude Ionosphere ◽

Electron Density Profiles

Abstract. Simultaneous observations of OI 777.4 and OI 630.0 nm nightglow emissions were carried at a low-latitude station, Allahabad (25.5° N, 81.9° E; geomag. lat. ∼  16.30° N), located near the crest of the Appleton anomaly in India during September–December 2009. This report attempts to study the F region of ionosphere using airglow-derived parameters. Using an empirical approach put forward by Makela et al. (2001), firstly, we propose a novel technique to calibrate OI 777.4 and 630.0 nm emission intensities using Constellation Observing System for Meteorology, Ionosphere, and Climate/Formosa Satellite Mission 3 (COSMIC/FORMOSAT-3) electron density profiles. Next, the electron density maximum (Nm) and its height (hmF2) of the F layer have been derived from the information of two calibrated intensities. Nocturnal variation of Nm showed the signatures of the retreat of the equatorial ionization anomaly (EIA) and the midnight temperature maximum (MTM) phenomenon that are usually observed in the equatorial and low-latitude ionosphere. Signatures of gravity waves with time periods in the range of 0.7–3.0 h were also seen in Nm and hmF2 variations. Sample Nm and hmF2 maps have also been generated to show the usefulness of this technique in studying ionospheric processes.

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